1. Field of the Invention
The invention relates to a centralizing device for maintaining a well conduit in a central position with respect to a well bore.
2. Description of the Prior Art
Conduit centralizers, such as casing centralizers, have long been employed with well casings inserted in well bores. The centralizer commonly comprises two axially spaced pairs of collar members which are generally formed from a pair of hinged interconnecting collar segments to permit the rings to be positioned on the casing in snug but slidable relationship thereto. The axially spaced rings are attached to opposite ends of a plurality of outwardly bowed portions of the leaf spring members spaced around the periphery of the collars. The outwardly bowed portions of the leaf springs are proportioned to engage the well bore and to be compressed inwardly by such engagement, thus exerting a centralizing force on the casing to which the centralizer is applied. Normally the centralizer is moved into the well with the casing by a clamping ring which is mounted securely to the exterior of the casing at a position between the two spring connected slidable collars.
Because of the ever increasing depths of modern wells, requiring a large number of casing centralizers to be employed for each well, there has been great emphasis in the well tool industry to minimize the cost of centralizers without in any mannder reducing their effectiveness. It has previously been proposed, for example in U.S. Pat. No. 4,088,186 to Callihan, et al, to fabricate the pivotally interconnected slidable collars from stampings to minimize the manufacturing costs thereof.
In addition to reducing manufacturing costs, it is also necessary to rduce shipping and handling costs and eliminate any unnecessary elements used to fabricate each centralizer. For example, a minimum number of bowed leaf springs necessary to adequately center a pipe should be used to any given application or size.
It is also important that the sliding collars, when assembled, have an internal diameter closely approaching that of a true cylinder, and an internal diameter exceeding the diameter of the casing to which it is to be assembled by only a few thousandths of an inch so that a snug sliding fit of the slidable rings on the casing is achieved. It has not been possible to achieve each of these objectives with the centralizers heretofore utilized in the art.